The present invention relates to a control device for controlling reconditioning of a liquid treatment system, in particular regeneration of a water conditioning or softening apparatus having a control valve with a first or main piston and a second or brine piston.
Conventional liquid treatment apparatus, such as water softeners, require periodic regeneration of the resin bed used to treat the incoming raw water to obtain soft water. Typically, in a stage known as eduction, a brine solution is passed through the resin bed to chemically recharge the resin. The resin is then rinsed with raw water to remove any traces of the brine. In some cases, the eduction step is preceded by a backwash step, in which the flow of incoming water is reversed to remove sediment which has been separated from the water during the conditioning operation and which may interfere with the softening operation. The latter are known as "five cycle" systems, wherein regeneration involves a backwash, a brine rinse, a slow rinse a fast rinse and a refilling of the brine tank. The length of time consumed by each of the steps in the regeneration cycle is a factor of the condition of the raw water being treated.
As is well known in the art, water softeners are provided with various mechanisms for initiating regeneration. Some of such mechanisms are clock operated, and are triggered to begin at a preset time of day, while others are triggered by a threshold volume of treated water. Still other mechanisms trigger regeneration by a condition of the resin bed.
Conventional water conditioner control valves employ separate pistons for controlling the main flow of the raw water between source, the treatment tank and the drain on the one hand, and between the treatment tank, the brine tank and the drain on the other. Some such valves are also provided with cam mechanisms for controlling the position of at least one of the pistons.
A main drawback, however of conventional softener control valves is that the piston rods of such valve pistons are biased against the cam motion by spring force. Over time, the spring force changes, reducing the accuracy and efficiency of the operation of the valve. In other applications, the cam rotates transversely to the longitudinal axis of motion of the pistons, and a relatively complex mechanical linkage is required to transfer the piston movement instructions from the cam.
Another drawback of conventional water conditioner valves is that the existing cam surfaces have dwell points which do not accommodate the inertia of a driving motor. More specifically, conventional water conditioner valve control systems employ an electric motor to rotate the cam, which then causes desired regeneration movement of the valve pistons. During the regeneration cycle, the motor stops at varying intervals while certain operations of the cycle are performed. Once the signal is generated to stop the motor, the internal gears and linkages of the motor have some inherent inertia, which causes the motor to turn slightly after being turned off. In some cases, this inertial movement can cause unwanted movement of the cam, and consequential disruption of the regeneration cycle.
The configuration of conventional cam dwell points has been ineffectual in solving this problem. The length of prior art cam dwell points has also been inadequate, in that the switch signals for operating the motors have a designated duration. Depending on the speed of the motor, if the dwell point is too short, there may be insufficient time to receive the entire signal for directing the motor to cease rotation.
Still another problem of conventional water conditioner control valves is that they are inefficient because the duration of the fast rinse portion of the regeneration cycle is a function of the brine tank refill time.
Accordingly, a first object of the present invention is to provide an improved water conditioner control valve which positively controls the operation of the main and brine pistons in both operational directions.
Another object of the present invention is to provide an improved water conditioner control valve which does not require extensive linkages to translate the rotational movement of the cam into linear displacement of the main and brine pistons.
Yet another object of the present invention is to provide an improved water conditioner control valve in which cam dwell points are configured to accommodate motor inertial movement after motor shut down.